Estrogen flips testosterone gene switch.
Talk about an odd couple. A new study suggests that estrogen, frequently considered the quintessential female hormone, can turn on genes by binding to the same protein that responds to testosterone and other androgens, the so-called male hormones.
This unexpected union only activates genes in the presence of a matchmaker Matchmaker - A language for specifying and automating the generation of multi-lingual interprocess communication interfaces. MIG is an implementation of a subset of Matchmaker. protein called [ARA Ara or Arrah (both: ŭ`rə), city (1991 pop. 157,082), Bihar state, NE India, on the Son Canal. A major road and rail junction, it is the administrative center for a district that produces grain, sugarcane, and oilseed. .sub.70], however, reports a research group led by Chawnshang Chang of the University of Rochester The University of Rochester (UR) is a private, coeducational and nonsectarian research university located in Rochester, New York. The university is one of 62 elected members of the Association of American Universities. (N.Y). He and his colleagues describe their study in the May 12 Proceedings of the National Academy of Sciences The Proceedings of the National Academy of Sciences of the United States of America, usually referred to as PNAS, is the official journal of the United States National Academy of Sciences. .
The new finding hints that estrogen may play a significant role in the development of male sex organs, the investigators contend. They also speculate that estrogen's apparent ability to mimic androgens could help explain how some prostate cancer prostate cancer, cancer originating in the prostate gland. Prostate cancer is the leading malignancy in men in the United States and is second only to lung cancer as a cause of cancer death in men. cells thrive despite treatments that eliminate androgens, which are usually necessary for prostate cells to survive.
"Our finding provides one alternative explanation for why totally blocking androgens doesn't completely block androgen receptor activity," says study coauthor Shuyuan Yeh.
While scientists reject a simplistic sim·plism
The tendency to oversimplify an issue or a problem by ignoring complexities or complications.
[French simplisme, from simple, simple, from Old French; see simple categorization of estrogen and testosterone as female and male hormones--both sexes make various forms of estrogens Estrogens
Hormones produced by the ovaries, the female sex glands.
Mentioned in: Acne, Polycystic Ovary Syndrome
n. and androgens--the hormones were thought to regulate largely distinct groups of genes. Estrogens latch onto so-called estrogen receptors, which in turn bind to and activate select genes. Similarly, testosterone and related hormones bind to androgen receptors, which turn on a different array of genes.
Chang's group, which years ago discovered the androgen receptor, more recently found that the presence of [ARA.sub.70] magnifies the receptor's response to androgens. The researchers then decided to reexamine re·ex·am·ine also re-ex·am·ine
tr.v. re·ex·am·ined, re·ex·am·in·ing, re·ex·am·ines
1. To examine again or anew; review.
2. Law To question (a witness) again after cross-examination. whether estrogens can turn on genes controlled by the androgen receptor. Past studies had indicated that estrogen could do so only when present in much higher concentrations than those found naturally in the body or when the androgen receptor has a mutation that makes it responsive to estrogen.
Working with cells genetically engineered to make [ARA.sub.70] and the androgen receptor, the investigators found that, in the presence of [ARA.sub.70], one form of estrogen activates some of the genes normally turned on by the receptor in response to androgen.
Further test-tube experiments identified a mutation in the androgen receptor that blocks estrogen's ability to turn on those genes--without affecting an androgen's ability to do so. The team also discovered that a man with abnormally developed reproductive organs had the same mutation. His androgen receptor's inability to respond to estrogen may help explain those developmental problems, the investigators suggest.
Several androgen researchers contacted by Science News questioned whether the new findings truly establish that estrogen interacts with the androgen receptor in the body.
"This won't be enough to get people to accept that estrogen acts through the androgen receptor, but it raises the possibility. It's provocative," says Steven P. Balk balk
the action of a horse when it refuses to obey a command to which it usually responds. See also jibbing. of Beth Israel Hospital See:
The researchers are in the process of creating mice with a defective [ARA.sub.70] gene, animals they hope will help further elucidate estrogen's relation to the androgen receptor. If estrogen does activate genes controlled by the androgen receptor, drugs that interfere with the function of [ARA.sub.70] may block this process and thus prove a useful addition to treatments for prostate cancer, notes Yeh.